#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int maxn=3e5+5;
int n,s[2],a[maxn],b[maxn];
int vis[maxn];
vector<pair<int,pair<int,int>>>v;
ll ans;
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
cin >> n >> s[0] >> s[1];
for(int i = 1;i <= n;i++){
cin >> a[i] >> b[i];
v.push_back({a[i]-b[i],{a[i],i}});
}
sort(v.begin(),v.end());
reverse(v.begin(),v.end());
for(int i = 0;i < s[0];i++) ans += v[i].second.first,vis[v[i].second.second]=1;
vector<int>nw;
for(int i = 1;i <= n;i++){
if(vis[i]) continue;
nw.push_back(b[i]);
}
sort(nw.begin(),nw.end());
reverse(nw.begin(),nw.end());
for(int i = 0;i < s[1];i++) ans += nw[i];
cout<<ans;
}
